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Thread: Evolution and Cancer

  1. #1 Evolution and Cancer 
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    First of all hello,

    I have been looking for a science based forum and I have found heaven!

    Anyway im a Student in Bristol at UWE studting Environmental Science and Health and Safety. I am a huge Richard Dawkins fan and have or am reading, The God Delusion, Selfish Gene, Blind Watchmaker and also Bertran Russell Religion and Science. So you can see where Im coming from as an atheist, a scientist, and I harbour huge interests for Evolutionary Science and Genetecism. All that said, im young and still learning and still being educated, and I hope to take that to another level on these forums. Anyway...

    My opening question is formed from watching that US series, Heroes. Series about Genetecism and Evolution..in a not very serious way basically. But anwyay...they mentioned soemthing about cancer being a part of evolution and a way in which natural selection will wipe out a species and a way in which natural selection goes forward.

    Now I'm not saying I believe that as...well....its fictional TV and people can fly in it etc

    But I am interested in hearing peoples opinions on how cancer affects evolution and natural selection...and where it comes into it all...

    Cheers in advance guys


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  3. #2  
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    It wouldnt affect evolution if it occured in later life after the person has reproduced, but perhaps if there was a tendency in early lif this could be somewhat valid, (IMO)!


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    ok, i'm watching heroes as well, but never heard anyone in the series say that...coulda missed it tho

    but of course cancer plays a role in natural selection...it's a part of it

    if you get cancer, you die (quicker), or at least, people with cancer are more likely to die than people without
    people who are resistant to cancer or don't get it that quickly live longer than people who aren't/do get it, and thus have the ability to create more offspring...offspring with those genes responsible for the resistance to cancer.
    this means the ratio of people resistant to cancer/vurnerable to cancer will turn in favor of the people who are more resistant to it(for whatever reason that is, doesn't really matter)

    so eventually(unless a cure for cancer is found) all humans will become more resistant to cancer(this, of course, will take hundreds if not thousands of years...)

    that's the only/most obvious way i can see cancer will affect natural selection(and thus evolution)
    grtz.
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    Episode 9 or 10 it was...im ahead of the UK showings but I see your in Holland anyway...im looking for quote

    Is it not possible over these thousands of years that the body may not become resistant and our species could fall to this?
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    fatal error, what you say is only true if the person has not yet reproduced, if someone has already had children then it's irrelevant whether or not or indeed when they develop cancer, they have already passed on their gene, evolution no longer matters (for them).

    Hence mankind will never genetically erradicate cancer, in fact it may become more of an issue with our increasing longevity.

    Also, with increased treatment & survivl rates for cancer, this could lead to an increase in the number of offspring being produced who have a tendency to develop cancer at an early age as their parent may have survived having it at a young age.
    Note that modern medicine in a way acts against evolution in that almost all offspring survive (in humans), the ones with weaker/disadvantageous genes do not die.
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    Quote Originally Posted by Robbie
    fatal error, what you say is only true if the person has not yet reproduced, if someone has already had children then it's irrelevant whether or not or indeed when they develop cancer, they have already passed on their gene, evolution no longer matters (for them).
    Only sort of. Evolution is not about the reproduction of the individual organism but the reproduction of genetic material. Humans like many species, evolved as social beings to maximize survival. Social animals 'play the odds'. Wolves, ants, humans,bees, termites and so on have investment in not only our own genetic material but that of our family, clan and so on. It's in out genetic interest for our sister, son, cousin, etc. to multiply. In fact their collective success might be worth more than my individual reproductive success. Strategies become mathematical formula. Odds as fined tuned as those at a Las Vegas blackjack table. Dying for one's country is an extreme runaway tangent of the strategy. Humans have group identification literally hard wired into our genetic material.
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    Re what is in the interest of the organism. Why cancer? Is it self destruction?

    It depends what is the focus of genetic reproduction. Is the organism the individual multicelular human or are the organisms the individual packets of genetic material inside each of the couple trillion cells that come together to make up a human? There are two ways of looking at 'a human'...as one or as a collection of trillions with a common goal. All the cells have made a pact or alliance to work together towards a common goal...all benefit. Symbiotic relationship at its most finely tuned.

    But what if an opportunity arises for a group of those cells to 'break out' and reproduce beyond their 'alloted expectation'? why not go for it? The interest of those cells is no longer in the collective good (a bit of a loaded word) but in themselves. It actually always has been but they've just never had a chance 'to get away' with it before. The other cells within the body keep them in check.

    In it's crudest form think of a bunch of guys who get together and rob a bank (or make a human organism). they need eachother to pull the heist and do the cover up, fence the goods and so on.They all watch each other like hawks and guard their interests by keeping each other in check through elaborate alliances and strategies. One of the guys ( what becomes cancer) sees an opportunity to get away with all the loot and goes for it. Genetic material within every cell is selfish and is looking out for itself and stays loyal as long as it's in that interest.
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    jellyologist: I totally agree that's what I was getting at, reproduction of genetic material, as long as an organism has passed on its genetic material by producing offspring, it's own genetic make up no longer play a role in evolution.

    Lets say a mother develops cancer at age 30 (& subsequently dies). That can still be passed onto her son/daughter if she has the child before developping the disease. Similarly, the child may develop it at a similar age, but that still doesnt matter if they have children before that. Their genes are still being passed on/proliferating despite the genetic weakness of developping the disease at a young age; evolution/natural selection does not have any effect.

    It only matters if the original "mother" dies before having children whereby her genes will not be passed on.

    As for your individual cell idea, it is not so much the other cells which keep an individual cell in check as it is the regulatory proteins within the cell. DNA (should) regulates its own replication by having genes which encode proteins which reglate it. Cells obey commands for apoptosis and undergo cell death, they are not "trying" to break free.
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  10. #9  
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    Quote Originally Posted by Robbie
    jellyologist: I totally agree that's what I was getting at, reproduction of genetic material, as long as an organism has passed on its genetic material by producing offspring, it's own genetic make up no longer play a role in evolution.

    Lets say a mother develops cancer at age 30 (& subsequently dies). That can still be passed onto her son/daughter if she has the child before developping the disease. Similarly, the child may develop it at a similar age, but that still doesnt matter if they have children before that. Their genes are still being passed on/proliferating despite the genetic weakness of developping the disease at a young age; evolution/natural selection does not have any effect.

    It only matters if the original "mother" dies before having children whereby her genes will not be passed on.
    okay, but let's look at it in the long run....eventually, if the genes keep getting passed on and on, something will have to give imo.

    there will, inevitably, eventually be a generation that dies before having children, which will stop the genes from being passed on

    i have to admit though, my statement about all humans becoming resistant to cancer eventually, and through natural selection was a bit stupid. It would require all of our DNA to somehow not be affected by mutagens, retroviruses or radiation anymore
    I guess when that happens, the cells won't look like anything we have now anymore...

    i don't doubt however, that a cure will eventually be found
    grtz.
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  11. #10 Re: Evolution and Cancer 
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    Quote Originally Posted by DawkinsisGod
    ...I am interested in hearing peoples opinions on how cancer affects evolution and natural selection...and where it comes into it all...
    From a selfish-gene's standpoint cancer may be beneficial. Cancer kills about a third of all people who die of diseases of old age. This clears out unproductive members of the population and leaves more resources available for the younger ones who can propagate those selfish genes. Cancer may even be a "tool" of the selfish gene, evolved as a survival mechanism.

    Another POV would be that cancer manifests from parasitic genes within the genome, and that these "parasites" are used endosymbiotically by "healthy" genes to cull the aging and dependent ones from a population.

    —Crabby
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    That's interesting alright as, after a point, evolution doesn't promote longevity.

    However, I think your parasitic genes idea is a bit mad, sounds a bit lik intelligent design. Cancer is from accidents on the genome/loss of regulation, its not "meant" to happen
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  13. #12 Genetic parasites 
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    Quote Originally Posted by Robbie
    ...I think your parasitic genes idea is a bit mad, sounds a bit lik intelligent design. Cancer is from accidents on the genome/loss of regulation, its not "meant" to happen
    Well, one theory that interests me (Wm. Hamilton's, I think) concerns the evolution of sex: Sex is a strategic maneuver used by genes to avoid or escape their genetic parasites. Gamete formation (meiosis) and eventual fertilization would act as critical pathways that prohibite (most of the time) alien genes from entering the "proper" genome.

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    That couldn't really be true (or at least not a very efficient mechanism) if you note that more than 50% of our genes are junk DNA! How exactly does meiosis prevent this occuring?
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  15. #14  
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    Quote Originally Posted by Robbie
    That couldn't really be true (or at least not a very efficient mechanism) if you note that more than 50% of our genes are junk DNA! How exactly does meiosis prevent this occuring?
    Yes, a lot of junk gets through, or has gotten through over the eons of evolution. I couldn't say where all the introns came from, but some of them could have been horizontally transfered from other species and did not present a parasitic problem to the genome.

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  16. #15 Re: Evolution and Cancer 
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    Quote Originally Posted by Crabby
    Quote Originally Posted by DawkinsisGod
    ...I am interested in hearing peoples opinions on how cancer affects evolution and natural selection...and where it comes into it all...
    From a selfish-gene's standpoint cancer may be beneficial. Cancer kills about a third of all people who die of diseases of old age. This clears out unproductive members of the population and leaves more resources available for the younger ones who can propagate those selfish genes. Cancer may even be a "tool" of the selfish gene, evolved as a survival mechanism.

    Another POV would be that cancer manifests from parasitic genes within the genome, and that these "parasites" are used endosymbiotically by "healthy" genes to cull the aging and dependent ones from a population.

    —Crabby
    Could be but until recently (in evolution time perspective) cancer was an insignificant cause of death....as was organ failure of any type. Most death (according to evidence from anthropology) was trauma, starvation, disease predation (on humans), parasites and, if someone lived to an older age (35 years) tooth abscess and resulting infections.

    Man is a social animal and culling the elder is a positive or negative according to the particular needs of a society. If an older sick wolf in a wolf pack or grandpa among humans was a burden, then hunter/gatherers would have developed social means of getting rid of grandpa either by just leaving him behind or some social custom of dignified departure. The Innu (Eskimos) in northern Canada left the no-longer-useful elderly with a bit of food. No words or emotions were espressed. The Blood Indians who live near us used to have a big celebration and then turn their backs while the old person walked away towards the sun. That night all the children would watch the skies for the first shooting star which was the spirit being taken on its jouney to meet the ancestors. More shooting stars were seen as the departed searching out the spirits of animals he had killed to request they continue to send their young to the people.
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  17. #16  
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    Some of you have written about being resistant to cancer, but I have never heard about that before. I can't understand it from what I know about the sickness. Can somebody explain it to me?
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